1. Field
The present disclosure relates to a travel control apparatus for a four-wheel drive vehicle and a travel control method for a four-wheel drive vehicle.
2. Description of the Related Art
For example, as disclosed in Japanese Patent No. 4368271, it is known that in a conventional four-wheel drive vehicle, when a failure occurs due to a functional defect of four-wheel drive travel control, the four-wheel drive control is stopped and shifted to two-wheel drive control. When the four-wheel drive control is stopped and shifted to the two-wheel drive control, a large drive torque applied to the wheels may cause unstable behavior of the vehicle. In order to prevent the unstable behavior of the vehicle, the four-wheel drive vehicle disclosed in Japanese Patent No. 4368271 controls a throttle opening such that when the drive torque (target transmission torque) to the rear wheels is greater than or equal to a predetermined value, the throttle opening is reduced and the four-wheel drive control is stopped and shifted to the two-wheel drive control, whereas when the drive torque to the rear wheels is less than the predetermined value, the four-wheel drive control is stopped and shifted to the two-wheel drive control without reducing the throttle opening.